1. Field of the Invention
The present invention relates to a water inlet valve, and more particularly to a water inlet valve which can stop water inflow in time under the condition that water tank accessories and a water tank fail.
2. Description of the Prior Art
A conventional water inlet valve comprises a water inlet pipe, a top cover, a water stop pad, a back-pressure pad, a swing arm, and a buoy. The lower end of the water inlet pipe is installed on a water supply pipe of a water tank. The top cover is installed on the upper end of the water inlet pipe. The interior of the water inlet pipe is formed with a water inlet cavity. The water inlet cavity is formed with a water stop surface having a water inlet. The water stop pad is installed in the water inlet cavity, corresponding in position to the water inlet and located above the water stop surface. The top cover is formed with a back-pressure hole. The middle section of the swing arm is pivotally connected to the top cover. One end of the swing arm faces the back-pressure hole and is installed with the back-pressure pad. The other end of the swing arm is connected with an adjustment rod of the buoy. Seal members are provided between the components to ensure water tightness. During use, when the water level in the water tank descends, the buoy will descend by gravity to bring the swing arm to deflect. The back-pressure pad is to open the back-pressure hole. The water from the water supply pipe flows through the water inlet pipe, the water inlet, the top cover, and the back-pressure hole to the water tank for water inflow. When the water level in the water tank ascends, the buoy will ascend by buoyancy to bring the swing arm to deflect. The back-pressure pad is to close the back-pressure hole. The water cannot enter the water tank from the back-pressure hole of the top cover. The water stop pad is deformed by back-pressure force to seal the water inlet of the water stop surface to stop water inflow.
However, the water tank accessories (a water inlet valve, a drain valve, a button, and other sealing members) may fail after a period of time. For example, the drain valve cannot be closed tightly to leak slowly (a leak of less water), the part of the drain valve or the button fail and are unable to close to drain all the time (a leak of much water), or the water inlet valve is unable to stop water inflow to cause an overflowing. The aforesaid situations result in waste of water resources. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.